Container sealing machine

ABSTRACT

A machine for automatically securing round covers on a succession of round containers by means of sealing strips of a substantially U-sgaped cross section and a predetermined length by automatically inserting the adjacent rolled outer edges of a container and cover between two sealing rollers which are rotating in opposite directions to each other, and by then automatically inserting the two webs of a sealing strip between the sealing rollers and the rolled edges while the container with its cover is turned for at least one complete revolution about a vertical axis. The automatic insertion of the rolled edges of the container and cover between the sealing rollers is attained by suitable means for retracting the lower sealing roller in the axial and vertical directions from its sealing position underneath the upper sealing roller so as to permit the container and cover to be lifted in a vertical direction until the rolled edges have passed the lower sealing roller, and for then moving the lower sealing roller forwardly and pressing it upwardly against the rolled upper edge of the container.

United States Patent [72] Inventor Otto Meister Oehringen, Germany [21] AppL No. 804,1 I2 [22] Filed Mar. 4, I969 [45] Patented Feb. 9, I971 [73] Assignee Karl Huber Verpackungswerke Oehringen, Germany [32] Priority Mar. 5, 1968 [3 3] Austria A2,I24/68 [5.4] CONTAINER SEALING MACHINE 11 Claims, 9 Drawing Figs.

[52] US. Cl 113/30, ,113/1,113/120 [51] Int. Cl B2ld 19/00 [50] Field of Search 113/30, 114,120Y,120AA,1E

[56] References Cited FOREIGN PATENTS 1,358,587 3/1963 France 113/30 Primary ExaminerCharles W. Lanham Assistant Examiner-Michael J. Keenan Attorney-Craig, Antonelli, Stewart and Hill ABSTRACT: A machine for automatically securing round covers on a succession of round containers by means of sealing strips of a substantially U-shaped cross section and a predetermined length by automatically inserting the adjacent rolled outer edges of a container and cover between two sealing rollers which are rotating in opposite directions to each other, and by then automatically inserting the two webs of a sealing strip between the sealing rollers and the rolled edges while the container with its cover is turned for at least one complete revolution about a vertical axis. The automatic insertion of the rolled edges of the container and cover between the sealing rollers is attained by suitable means for retracting the lower sealing roller in the axial'and vertical directions from its sealing position underneath the upper sealing roller so as to permit the container and cover to be lifted in a vertical direction until the rolled edges have passed the lower sealing roller, and for then moving the lower sealing roller forwardly and pressing it upwardly against the rolled upper edge of the container.

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PATENIEUrrasrsn 3561386 I saw or 7 CONTAINER SEALING MACHINE The present invention relates to an automatically operating machine for closing the open upper end of each of a series of containers and especially filled round containers, such as cans, barrels, or the like, by means of round plate-shaped covers and by sealing strips which are bent so as to connect these covers to the upper edges of the containers.

More particularly, the invention relates to improvements in a machine of known type as disclosed, for example, the German Pat. GM. 1,877,508 which is provided with a mechanism for automatically feeding a sealing strip from a reel, bending the strip so as to have a substantially U-shaped cross section, and cutting off a section of the strip of a predetermined length as required for the closing operation. The frame of this machine is provided with a vertical post which has a head on its upper end which is slightly inclined relative to a horizontal plane and contains a pair of parallel shafts which are rotatably mounted in the head, are driven in opposite directions to each other by a common motor, and each of which carries on its lower end outside of the inclined heada sealing roller. These sealing rollers are adapted to receive the U-shaped sealing strip and, while pressing the adjacent outwardly projecting rolled edges of the container and cover against each other and turning the container and cover about a common vertical axis, to bend the lateral webs of the sealing strip tightly around these edges. In this closing operation, the upper sealing roller which is rotatable about a fixed axis therefore presses the upper web of the U-shaped sealing strip around and against the projecting edge of the cover, while the lower sealing roller while rotating is moved upwardly so as to press the lower web of the sealing strip around and against the projecting edge of the container. Both webs are thus bent by these rollers around these rolled edges and pressed toward each other, and thereby also press the cover tightly upon the container, while the container with its cover is turned about a vertical axis by the pressure of the rotating rollers on a rotatable supporting plate.

Although the sealing strip of the required length is fed automatically to the container, this known machine has the disadvantage that each container which is to be sealed has to be placed by hand upon its rotatable supporting plate and after being sealed also has to be manually removed. This feeding operation of each container to and upon the supporting plate cannot be carried out automatically since for sealing containers of differentheights, this known machine requires the vertical spindle carrying the supporting plate to be raised accordingly since the post carrying the sealing rollers on its head is not adjustable. It was therefore impossible to connect such a sealing machine tothe container-conveyor of a preceding filling machine since such a conveyor usually operates on a substantially uniform level and therefore also requires the container-supporting plate of the sealing machine to be disposed at such a level. Since in this machine each container had to inserted by hand into the sealing position by passing the rolled edges of the "container and cover from the front between the opened sealing rollers, the lower sealing roller was rotatably mounted so as to be located at all times substantially vertically underneath the upper sealing roller. The lower sealing roller was therefore not slidable back and forth in its axial direction which is a prerequisite to a fully automatic sealing operation since such an operation would require the lower sealing roller to be withdrawn from its actual sealing position underneath the upper sealing roller in order to permit the container to be lifted vertically by its supporting plate until the rolled edges of the container and cover have passed the lower sealing roller and the edge of the cover has been moved into engagement with the upper sealing roller. Even after the rolled edges of the container and cover were inserted by hand from the front between the sealing rollers, the actual sealing operation of this known machine could not be started automatically, but it required the operation of a foot pedal for lifting the supporting plate together with the container and cover so as to move the rolled edge of the cover into engagement with the upper sealing roller and then to press the lower sealing roller against the rolled edge of the container.

It is an object of the present invention, to provide a scaling machine of the general type as above described which, however, eliminates the mentioned disadvantages of the known sealing machines and is adapted to be easily adjusted to seal successive series of round containers of different dimensions and, after being adjusted to containers of one size, to seal a continuous succession of these containers fully automatically.

For attaining this object. the present invention provides manually operated means of a very simple type for effecting a preliminary adjustment of the vertical post the head of which carries the shafts of the sealing rollers by raising or lowering this post together with the sealing rollers so as to be in a position in accordance with the particular height of the containers to be sealed from the level of the conveyor surface which feeds one conveyor at a time to a position underneath the rollers, and/or for shifting the post with its head in a horizontal direction so as to adjust the position of the sealing rollers in accordance with the differences in diameter of several series of containers.

Another feature of the invention consists in the provision of cam means for automatically shifting the lower sealing roller simultaneously forwardly and upwardly toward the projecting upper edge of the container against the action of tension springs which tend to draw the lower sealing roller in the op posite direction. Thus, in the operation of the machine, the supporting or centering plate on which the container rests which is to be sealed is at first lifted either hydraulically or by mechanical means slightly above the level of the conveyor surface in order to move the projecting edge of the cover on the container into engagement with the upper sealing roller which rotates about a fixed axis, while at the same time the lower sealing roller is moved by the cam means forwardly and upwardly against the action of the tension springs so as to press this roller against the projecting upper edge of the container. Due to the positive rotation of both sealing rollers in opposite directions by a motor and its gearing, the container with its cover is then turned on and together with the lifting plate. The two webs of the U-shaped sealing strip are then pushed between the sealing rollers and the rolled edges of the container and cover and are bent toward each other and around these edges. When the container has been completely closed by the sealing strip, the centering plate is again lowered to its original level and the lower roller is drawn back downwardly and toward the rear by the tension springs. Thereafter, the closed container is ejected from the machine and a new container is moved to and upon the centering plate at the sealing station underneath the sealing rollers.

Another feature of the invention consists in the possibility of either connecting the sealing machine to the conveying mechanism of a preceding machine, for example, a container filling machine, or of providing it with its own container-feeding conveyor, or of connecting its own conveyor to a preceding machine or the conveyor thereof. Similarly, the power for raising and lowering the centering plate may be either derived from a preceding machine or the conveyor thereof or it may be produced by an electric motor or a hydraulic or pneumatic unit separate from the preceding machine.

According to a preferred embodiment of the invention, another feature thereof consists in the provision of a container feeding mechanism which either comprises a roller conveyor or conveyor belt and a turntable which is operatively connected to the end of this conveyor and is intermittently rotated and provided with a centering plate which has a plurality of pockets for receiving one container after another from the conveyor on separate centering plates which at this time are slightly lifted above the surface of the turntable into the hollow bottom of the container so as to center the container and hold it during the intennittent rotation of the turntable within its pocket until it reaches the sealing station underneath the sealing rollers when this centering plate lifts the container into engagement with the upper sealing roller.

Another feature of the invention consists either in the provision of a lever or a photoelectric cell which is actuated to start the feeding movement of the sealing strip by a suitable clutch when the next container to be sealed approaches or arrives at the sealing station.

Still another feature of the invention consists in the provision of an ejector which may be either positively driven to eject the closed container from the sealing machine or which, according to the embodiment of the invention in which the container-feeding mechanism includes a turntable, may simply consist of a deflector with an inclined surface along which the closed container slides while being moved by the turntable until it falls off the outer edge of the turntable.

From all of these features it is evident that, except for a preliminary manual adjustment which might be required for adjusting the machine to the particular size of the containers, the machine according to the invention operates fully automatically to close and seal successively any desired number of filled containers of the same size by means of plate-shaped covers and sealing strips which are bent to a U-shaped cross section and cut to the required length during the operation of the machine. It is further evident from the previous descript on that this machine may either by operatively associated with a preceding machine, for example, a container filling machine, and the conveying means thereof, and that rega Jless of the diameter of the container to be sealed, the vertical axis of the container which has been moved to the sealing station may always extend upwardly from the same point since the manual adjustment means according to the invention permit the sealing rollers to be moved to the proper operating position relative to each container of a series to be sealed.

These and numerous additional features and advantages of the present invention will become further apparent from the following detailed description thereof which is to be read with reference to the accompanying drawings, in which:

FIG. shows, partly in section, a front view of a sealing machine according to the invention which is partly operated hydraulically and in which the containers are fed to the sealing station y by the conveyor of a preceding machine, for example, a container filling machine;

FIG. 2 shows a top view of the machine according to FIG. I but with the strip-feeding shaping and cutting mechanism in a position offset from its normal position for greater clarity of illustration;

FIG. 3 shows an end view of the machine as seen from the left of FIGS. 1 and 2, from which, however, the conveyor is omitted;

FIG. 4 shows, partly in section, a front view of another sealing machine according to the invention which is operated electrically and mechanically and in which the conveying mechanism is also driven by this machine;

FIG. 5 shows a top view of the machine according to FIG. 4, in which similarly in FIG. 2, the strip-feeding shaping and cutting mechanism is shown in a position offset from its normal position;

FIG. 6, shows an end view of the machine according to FIGS. 4 and 5, but without the conveying mechanism;

FIG. 7 shows an enlarged detail view of the lower sealing roller and its guiding, adjusting and driving means as shown in FIG. 1;

FIG. 8 shows an enlarged end view of the means according to FIG. 7, as seen from the left thereof, but without the housing; while FIG. 9 is an enlarged cross section which is taken along the line A-B of FIG. 4 and shows the mechanical elevating means of the lifting plate.

As illustrated in FIGS. 1 to 8 of the drawings, the sealing machine according to the invention comprises a frame 1 which, although provided with wheels for moving the machine when not in operation to different locations, is to be mounted in a fixed position when sealing operations are to be carried out. On this frame I a vertical post 2 is slidably mounted so as to be adjustable in the longitudinal horizontal direction of the machine by a handwheel 2' and also in a vertical direction by a handwheel 2" in order to permit sealing operations to be carried out on different series of round containers of different diameters and/or different heights. On its upper end, post 2 carries a head 3 which extends in the longitudinal direction of the machine and the longitudinal axis of which is slightly inclined to a horizontal plane. On the side of the machine frame 1 opposite to that on which the handwheels 2' and 2" are located, a removable reel 4 is rotatably mounted from which a flat strip material 5 may be withdrawn by and fed to a strip-feeding shaping and cutting mechanism 6 which is mounted on the head 3 and which, when the sealing machine is started to seal a container, bends the flat material so as to form a sealing strip of a U-shaped cross section, cuts off a section of this strip of a certain but adjustable length as required for each sealing operation, and feeds this U-shaped strip to the container to be sealed. The head 3 of post 2 forms a housing in which a pair of parallel shafts 9 and I0 are rotatably mounted. The upper shaft 9 which is not slidablc in its axial direction and rotatable about a fixed inclined axis in bearings which are rigidly secured to this housing 3 carries on its lower front end outside of the housing an upper sealing roller 7, while the lower shaft 10 carries on its front end a lower scaling roller 8. as shown particularly in FIGS. 7 and 8, this lower shaft 10 is rotatably mounted within a bearing sleeve II which, in turn, is movably mounted in housing 3 for lifting and lowering the lower shaft 10 and its sealing roller 8 and for shifting this shaft and roller in the axial direction for the purposes as subsequently described. The rear end of housing 3 carries an electric motor 12 which by means of a gear unit drives the upper shaft 9 carrying the sealing roller 7 and the lower shaft I0 carrying the sealing roller 8 in opposite directions. This gear unit includes a gear I3 which is secured to the rear end of the lower shaft 10 as indicated in FIG. 7, and it further includes a gear or sprocket wheel 14 which is connected, for example, by a chain 15, to another gear or sprocket wheel I6 on the drive shaft of the strip-feeding, shaping and cutting mechanism 6.

By means of the handwheels 2' and 2" it is possible to adjust the entire housing 3 and thus also both sealing rollers in horizontal and vertical directions in order to adjust the position of the latter in accordance with the upper rolled projecting edges of containers and covers of different diameter and/or heights before a series of containers of the same size are being sealed. These adjustments avoid the necessity of varying the normal level of a supporting and centering plate 25 at the sealing station on which the respective container 29 is placed which is next to be sealed. Before a sealing operation is started, this centering plate 25 may therefore be disposed at substantially the same level as the conveying mechanism which is adapted to feed one container 29 after another to this station. However, in order to lift the container 29 at the sealing station for a short distance in a vertical direction, for example, approximately 40 mm., so that the upper rolled edge of its cover will be moved past the lower sealing roller 8 and then into engagement with the upper sealing roller 7, it is necessary at this time to hold the lower sealing roller in a sufficiently retracted position in its axial direction before the container is lifted by its centering plate 25 by suitable means which may be operated, for example, hydraulically, as shown in FIGS. I to 3, or mechanically as shown in FIGS. 4 to 6 and 9. As soon as the rolled edge of the cover of the container has moved upwardly past the lower sealing roller 8 and into engagement with the upper sealing roller 7, the lower sealing roller 8 must be moved forwardly to a position underneath the rolled upper edge of the container and upwardly into engagement with this edge so that the container and cover will then be pressed together and, due to the rotation of both sealing rollers, the container will be turned on and together with the rotatable centering plate 25. The U-shaped sealing strip 5 is then fed by the mechanism 6 to the container so that the two webs of this strip enter between the sealing rollers 7 and 8 and the rolled edges of the container and its cover and, due to the shape of these rollers and their pressure against the sealing strip, the latter will be deformed around the rolled edges of the container and cover and seal the latter to each other.

For moving the lower sealing roller 8 toward the wall of the container and lifting it so as to press against the lower side of the rolled upper edge of the container, after the latter has been lifted by the centering plate 25, the bearing sleeve 11 of shaft 10 carrying the lower sealing roller, preferably has a square outer shape, as shown in FIG. 8, and is guided in a vertical direction between two pairs of cam shaped bearing members 22 which are rigidly secured to the housing 3. Bearing sleeve 11 further carries two pairs of rotatable rollers 21 which under the action of tension springs are held in constant engagement with the cammed front side of the earns 22, Underneath and parallel to bearing sleeve 11 and shaft 10 therein another shaft 17 is rotatably mounted in opposite walls of housing 3. This shaft 17 has rigidly secured thereto a pair of earns 18 and a lever 19. When the free end of lever 19 is pulled downwardly by one or more Bowden cables 23 or 23', shaft 17 will be turned about its axis and earns 18 will be pivoted so as to lift bearing sleeve 11 together with shaft 10 and sealing roller 8. Due to the shape of the fixed cams 22 which under the tension of springs 20 engage with the rollers 21, bearing sleeve 11 while being lifted will also be shifted in its axial direction so that the lower sealing roller 8 will be moved into engagement with and press against the lower side of the rolled upper edge of the container 29.

For lifting the centering plate 25, FIGS. 1 to 3 illustrate a hydraulic mechanism which comprises a cylinder and piston unit 26 which is operated by a hydraulic drive unit 27 including an electric motor and a pump, and a suitable electromagnetic control valve with a switch for operating the same. This hydraulic drive unit 27 is operated when a feeler or switch lever 28 is pivoted by a container 29 entering the sealing station on centering plate 25. The pivoting movement of lever 28 results in the actuation of an electric switch which, in turn, actuates the control valve of the hydraulic drive unit so that the hydraulic cylinder and piston 26 will then be operated to act upon the spindle 24 of the centering plate so as to lift the latter and thereby move the container 29 upwardly until its cover engages upon theupper sealing roller 7. This movement of spindle 24 is transmitted at the same time through the Bowden cables 23 to the lever 19 on shaft 17 so as to pivot the cam 18 and thereby move the lower sealing roller 8 axially toward the container and upwardly against the rolled upper edge thereof. The actuation of the switch for the electromagnetic control valve by the lever 28 also actuates a suitable electromagnetic clutch (not shown) so as to start the operation of the strip-feeding, shaping and cutting mechanism 6 so that the container 29 will then be closed and sealed. The actuation of this magnetic clutch also causes the actuation of an electric timing relay (not shown) until the sealing strip 5 has passed completely through the sealing rollers 7 and 8. When this relay is deenergized, the above-mentioned magnetic control valve is switched over so that the cylinder and piston unit 26 will lower the centering plate 25 to the level of the table surface 30. When the centering plate 25 reaches this position, it actuates another electric switch (not shown) which switches on the magnetic control valve of a further hydraulic cylinder unit 31 which causes an ejector lever 32 to be pivoted so that the sealed container will be ejected from the table surface 30. At the end of the forward stroke of the piston of the hydraulic unit 31 a further switch (not shown) will be actuated which switches back the magnetic control valve of this unit 31 so that the lever 32 will return to its initial position as shown in FIG. 2. As soon as a new container is moved toward its sealing position on the centering plate 25, it again actuates the switch.

lever 28, whereupon a new sealing operation will be initiated in the same manner as previously described.

In place of a switch lever 28, it is also possible to employ a in the embodiment of the invention as illustrated in FIGS. 1 to 3 it is assumed that the sealing machine is positively connected to a preceding machine, for example, a filling machine. and that the containers are fed up to the sealing station by the conveyor 33 of this preceding machine. Of course, the conveyor for the containers may also form a part of the sealing machine itself and be controlled either by the sealing machine or by a preceding machine.

Instead of feeding the containers 29 to the sealing station underneath the sealing rollers 7 and 8 by means of a separately driven conveyor or the conveyor of a preceding machine, for example, a filling machine, and instead of initiating the sealing operation by hydraulic means, it is also possible according to another embodiment of the invention as illustrated in FIGS. 4, 5, 6, and 9 to drive the conveying mechanism by the driving means of the sealing machine and to initiate the sealing operaphotoelectric cell 28' which, when the next container to be tion by mechanical means. This conveying mechanism which may, for example, be attached to the end of the conveyor of a preceding filling machine so as to receive the filled conveyors therefrom, comprises a suitable conveyor 40, for example. a roller conveyor, and a turntable 41 which is mounted on a vertical shaft 43. Via a gear unit an electric motor 42 drives the conveyor 40 and also a Maltese cross 43 which is connected to the turntable 41 and converts the continuous rotation produced by the motor 42 into an intermittent rotation of the turntable 41 so that during each revolution the latter will stop, for example, at each of six stations for the length of time as required for one complete sealing operation including the lifting and lowering of a centering plate 25 at the sealing station. The turntable 41 comprises a larger lower' plate 44 and removably secured thereto a smaller upper plate 45. The lower plate 44 is provided with circular apertures 46 each of which has a diameter substantially equal to the diameter of a centering plate 25 for the largest containers to be sealed on this machine. Plate 44 is further provided with radial slots 48 each of which extends from the periphery of table 44 to the respective aperture 46. The upper table 45 is provided with substantially semicircular pockets of diameter substantially in accordance with the diameter of the centering plates 25 for the particular containers to be sealed. lf centering plates 25 of a smaller diameter than necessary for the largest containers are to be employed, a slotted filling ring 47 of a suitable size is to be inserted into each aperture 46. The last section of the conveyor 40 is provided with a longitudinal slot which has the same width as each of the radial slots 48 as in table plate 44 and will be in straight alignment with the slot 48 at the receiving station when turntable 41 is stopped at this station. Underneath this slot in the conveyor 40 a small angular feed lever 49 is pivotably mounted on a drive rod which, while the conveyor 40 continues to move forwardly, is driven back and forth along the slot in the conveyor and in the slot 48 by means of a crank drive which like the conveyor 40 is driven by the motor 42. When feed lever 49 moves back while the conveyor continues to move forwardly, it engages with the front edge of the bottom of the next container 29 and is thereby pivoted downwardly against the action of its spring until it reaches the rear edge of this container. Lever 49 can then pivot upwardly and hook behind this container since during this time the forward movement of the next following container is stopped by suitable electromagnetic holding means. During the following forward movement of feed lever 49, it will push the container into the pocket of the upper table plate 45 at the receiving station until it rests on the centering plate 25 at this station, and its vertical axis is located on the circular path 50 of all centering plates 25. During the next return stroke of lever 49 the next following container 29 will be released from the magnetic holding means and be moved forwardly. Lever 49 can then again slide underneath and hook behind this container while the next following container is held back on the conveyor 40 by the magnetic holding means.

The spindle 51 of each centering plate 25 is slidable within a guide sleeve 52 which is secured to the table plate 44. On its lower end, each spindle carries a roller 53 which may run along a segmentally-shaped rail 54 which extends from the end of the receiving station to a point beyond which the closed container is ejected from the turntable 41. This rail 54 is located within such a horizontal plane that, as long as a roller 53 engages thereon, the upper surface of the associated centering plate 25 projects for a short distance above the plane of the table plate 44 so that the centering plate 25 will engage into the hollow bottom of the container and thereby center the same accurately on the circular path 50.

As illustrated particularly in H0. 9, a drive shaft which is rotatably mounted at the sealing station underneath the rail 54 and is driven by the gear unit of motor 42 carries a cam plate 55 which runs along a roller 56 which is rotatably mounted on one end of a two armed lever 57, the other end of which is pivotably connected to a lifting rod 58. The pivoting movement of lever 57 will thus result in a vertical movement of rod 58 so as to act upon the roller 53 and lift the spindle 51 in guide sleeve 52 and thus also the centering plate 25 with the container 29 thereon for the required distance until the rolled edge of its cover engages with the upper sealing roller 7, whereupon the sealing operation is started in the manner as has already been described. This, of course, requires the lifting stroke of rod 58 which is produced by cam plate 55 to occur in cycle with the intermittent movement of turntable 41. The end 01 lever 57 acting upon the lifting rod 58 also carries one end of at least one Bowden cable 23 the other end of which is secured to the lever 19 on shaft 17 for pivoting the earns 18 (FIG. 8) in the same manner and for the same purposes as described with reference to FIGS. 1 to 3. The strip-feeding, shaping and cutting mechanism 6 is also started in the same manner as already described, for example, by means of a lever 28' which is actuated by the container 29 which approaches the sealing station.

After each container 29 is sealed, it may be ejected from the turntable 41 by sliding along a fixed but adjustable deflector 59 during the further rotation of the turntable. Of course, in place of such a fixed deflector, it is also possible to provide an ejector which is movable mechanically so as to push the sealed container positively off the turntable 41.

Although my invention has been illustrated and described with reference to the preferred embodiments thereof, I wish to have it understood that it is in no way limited to the details of such embodiments but is capable of numerous modifications within the scope of the appended claims.

lclaim:

1. A sealing machine for automatically securing a round cover tightly upon each of a series of round containers so as to close an upper opening of said container by means of a sealing strip, said container and cover each having an outwardly projecting rolled edge adjacent to each other, said machine comprising a frame mounted in a fixed position at least when said machine is in operation and having a substantially horizontal table surface, an upper and a lower shaft rotatably mounted on said frame and extending in the longitudinal direction thereof and slightly inclined to said horizontal surface and having an upper and a lower sealing roller secured to the corresponding lower end of said shafts, first means for rotatably mounting said upper shaft in a fixed axial position in which said upper sealing roller is located above said table surface at a distance exceeding the height of each of said containers of said series to be sealed, second means for rotatably mounting said lower shaft so as to extend at all times substantially parallel to said upper shaft but adapted to pennit said lower shaft to be raised and lowered and also to be moved in its axial direction relative to said upper shaft, third means for continuously driving said shafts including said rollers in opposite directions to each other, said table surface having at least one aperture, a centering plate within said aperture having an upper surface normally disposed at the same level as said table surface, conveying mans means for periodically feeding one of said containers to and along said table surface and upon said centering plate at a sealing station in which the most forward point of said cover edge is substantially in vertical alignment with said upper sealing roller, resilient fourth means tending to maintain said lower shaft in a retracted position in which said lower sealing roller is axially retracted from and also lowered from its sealing position in which it is located substantially vertically underneath and spaced at a small distance from said upper sealing roller, fifth means for elevating said centering plate at said sealing station in a substantially vertical direction and first adapted to lift said plate from said normal level for the distance required to lift the container to be sealed until said edges have passed said retracted lower scalcr roller and said cover edge engages with said upper sealing roller, sixth means responsive to the operation of said fifth means for then axially sliding said lower shaft so as to move said lower sealing roller toward said container and to a position underneath said upper sealing roller and upwardly to said sealing position in engagement with said container edge, means for connecting said fifth and sixth means, said rotating sealing rollers then turning said container and cover on said centering plate about a vertical axis, and a strip feeding mechanism secured to said frame for then feeding a sealing strip of a substantially U- shaped cross section and a length at least equal to the circumference of said edges to said sealing rollers so that the two webs of said strip enter between said sealing rollers and said edges, whereby said sealing rollers while turning said container and cover together with said strip for at. least one complete revolution will press said webs toward each other and thereby deform them around said edges so as to seal said container tightly, said elevating means then being adapted first to release said sixth means so that said resilient fourth means will move said lower sealing roller back to its retracted position and then to lower said centering plate with said sealed container to said normal level, and means for then ejecting said sealed container from said table surface.

2. A sealing machine as defined in claim 1, further comprising a substantially vertical post having a housing on its upper end, said shafts extending through said housing and carrying said sealing rollers outside of said housing, said first, second, fourth, and sixth means being connected to and at least partly disposed within said housing, and manually operated means for moving at least said housing in a substantially horizontal longitudinal direction and for raising and lowering it in a substantially vertical direction, relative to said frame in order to permit the position of said sealing rollers to be adjusted in accordance with different series of containers of different heights and/or different diameters prior to the operation of said machine of sealing each of said different series.

3. A sealing machine as defined in claim 2, in which said second and sixth means comprise a bearing sleeve, said lower shaft extending through and rotatably guided by said bearing sleeve but nonslidable in its axial direction relative to said sleeve, said bearing sleeve having opposite plane outer surfaces parallel to each to other, at least two pairs of guide rollers rotatably mounted on said outer surfaces of said sleeve and spaced from each other, the guide rollers of each pair having a common axis extending transverse to the common longitudinal axis of said sleeve and said lower shaft, at least two pairs of bearing members rigidly secured to said housing, said bearing members of each pair having plane parallel surfaces facing and spaced from each other and extending in vertical directions, said plane outer surfaces of said bearing sleeve being disposed between and slidably guided in vertical directions by said plane surfaces of said bearing members, said bearing members having cam-shaped front surfaces, each of said cam surfaces having an upper part projecting more forwardly than the lower part, said resilient fourth means comprising tension springs connected to said bearing sleeve and to a rear part of said housing for maintaining said guide rollers on said bearing sleeve in constant engagement with said camshaped front surfaces and tending to draw said bearing sleeve downwardly and toward the rear, a shaft rotatably mounted in a fixed position in said housing underneath said bearing sleeve and extending parallel thereto, at least one lever secured at one end to said last shaft, and cam members secured to saidlast shaft and by the action of said tension springs being at all times in engagement with the lower side of said bearing sleeve, and at least one Bowden cable having one end connected to said fifth means and another end connected to the other end of said lever so that, when said centering plate has been raised sufficiently to lift said rolled edges past said lower roller, said other end of said lever will be pulled downwardly and said cam members on said last shaft will thereby be pivoted upwardly, whereby due to the engagement of said guide rollers with said cam-shaped front surfaces of said bearing members, said bearing sleeve together with said lower shaft and sealing roller will be moved in the axial direction toward said container and then upwardly so as to press said lower sealing roller against said rolled container edge.

4. A sealing machine as defined in claim 1, in which said fifth means comprise hydraulic means, and further comprising hydraulic means responsive to the lowering of said centering plate for actuating said ejecting means.

5. A sealing machine as defined in claim 1, in which said strip-feeding mechanism comprises a reel rotatably and removably mounted on said frame and carrying a supply of a flat strip material, and means for withdrawing said strip material from said reel, for bending said material to a substantially U-shaped cross section to form a sealing strip, for cutting off a section of said material of a predetermined but adjustable length as required for the following sealing operation and for feeding said sealing strip to said sealing rollers, and means responsive to the movement of a container to said sealing station for starting saidfeeding mechanism.

6 A sealing machine as defined in claim 1, in which said conveying means comprise a conveyor of, and driven by, a preceding machine and connected to said sealing machine so as to feed a new container to be sealed to said sealing station immediately prior to the beginning of the operation of said sealing machine or when the previously sealed container has been moved off said station, and means for detecting the arrival of a container at said sealing station and for then starting the operation of said fifth means.

7. A sealing machine as defined in claim 1, in which said conveying means are driven by the driving means of said sealing machine.

8. A sealing machine as defined in claim 1, in which said conveying means comprise a turntable rotatable about a central vertical axis, means for feeding containers to a receiving station of said turntable, continuously rotatable driving means for said conveying means, and means interposed between and connected to said driving means and said turntable for converting the continuous rotation of said driving means into an intermittent rotation of said turntable, each stop of said turntable having a length at least equal to one complete sealing operation including the lifting and lowering of a container by said centering plate at said sealing station, said turntable comprising a larger lower plate and a smaller upper plate con-. centrically secured to each other, said lower plate having a plurality of circular apertures equally spaced from said vertical axis and equally spaced peripherally from each other and each adapted to receive one of said centering plates having an upper surface normally disposed at the level of the upper surface of said lower plate forming said table surface, said upper plate having substantially semicircular outwardly open pockets in its outer peripheral wall, each of said pockets being coaxial with one of said apertures and, when stopped at said receiving station, being adapted to receive a container from said container-feeding means and to center it on said centering plate at said receiving station and to hold it thereon until said container reaches said sealing station and is then lifted by said centering plate, sealed, and lowered to said normal level, and said sealed container is then ejected from said turntable by said reflecting means.

' 9. A sealing machine as defined in claim 8, further comprising a segmentally-shaped guide rail mounted in a fixed horizontal position underneath said turntable and extending from a point near and forwardly of said receiving station to a point forwardly of said sealing station, as seen in the direction of rotation of said turntable, each of said centering plates being secured to the upper end of a spindle, a vertical guide tube for each spindle secured to said lower plate, and a small roller rotatably mounted on the lower end of each spindle projecting from said guide tube, said roller being adapted to roll upon and along said guide rail when a container is moved by said turntable away from said receiving station, whereby said centering plate carrying said container is lifted for a short distance above said normal level and engages into the hollow bottom of said container so as further to center and hold said container within its pocket of said upper plate during the further rotation of said turntable until said pocket has passed sealing station. I

10. A sealing machine as defined in claim 8, in which said container-feeding means comprise a conveyor continuously driven by said driving means, said lower plate having a radial first slot extending from each of said apertures to the periphery of said lower plate, the last section of the conveying surface of said conveyor adjacent to said turntable having a second slot adapted to be in straight alignment with the first slot in said lower plate at said receiving station, a feed rod underneath said second slot in said conveying surface, a small angular feed lever pivotably mounted on said feed rod and pivotable through said second slot, a spring tending to pivot said feed lever so that the free end thereof projects slightly above said conveying surface, a crank drive also driven by said driving means for said conveying means for reciprocating said feed rod to and from said turntable and for thus moving said feed lever along said second slot and said first slot at said receiving station, and means for arresting the forward movement of a second container on said conveyor during at least the last part of the rearward stroke of said feed rod, so that said feed lever can then slide underneath the first, forwardly moving container on said conveyor and then pivot upwardly and hook behind the bottom of said first container and, by the following forward stroke of said feed rod, move said first container into said pocket at said receiving station.

11. A sealing machine as defined in claim 8, in which said ejecting means comprise a deflecting member adjustable so as to extend at a certain fixed angle to the direction of rotation of said turntable to permit the sealed container to abut against and slide along said deflecting member during the further rotation of said turntable. 

1. A sealing machine for automatically securing a round cover tightly upon each of a series of round containers so as to close an upper opening of said container by means of a sealing strip, said container and cover each having an outwardly projecting rolled edge adjacent to each other, said machine comprising a frame mounted in a fixed position at least when said machine is in operation and having a substantially horizontal table surface, an upper and a lower shaft rotatably mounted on said frame and extending in the longitudinal direction thereof and slightly inclined to said horizontal surface and having an upper and a lower sealing roller secured to the corresponding lower end of said shafts, first means for rotatably mounting said upper shaft in a fixed axial position in which said upper sealing roller is located above said table surface at a distance exceeding the height of each of said containers of said series to be sealed, second means for rotatably mounting said lower shaft so as to extend at all times substantially parallel to said upper shaft but adapted to permit said lower shaft to be raised and lowered and also to be moved in its axial direction relative to said upper shaft, third means for continuously driving said shafts including said rollers in opposite directions to each other, said table surface having at least one aperture, a centering plate within said aperture having an upper surface normally disposed at the same level as said table surface, conveying mans means for periodically fEeding one of said containers to and along said table surface and upon said centering plate at a sealing station in which the most forward point of said cover edge is substantially in vertical alignment with said upper sealing roller, resilient fourth means tending to maintain said lower shaft in a retracted position in which said lower sealing roller is axially retracted from and also lowered from its sealing position in which it is located substantially vertically underneath and spaced at a small distance from said upper sealing roller, fifth means for elevating said centering plate at said sealing station in a substantially vertical direction and first adapted to lift said plate from said normal level for the distance required to lift the container to be sealed until said edges have passed said retracted lower sealer roller and said cover edge engages with said upper sealing roller, sixth means responsive to the operation of said fifth means for then axially sliding said lower shaft so as to move said lower sealing roller toward said container and to a position underneath said upper sealing roller and upwardly to said sealing position in engagement with said container edge, means for connecting said fifth and sixth means, said rotating sealing rollers then turning said container and cover on said centering plate about a vertical axis, and a strip feeding mechanism secured to said frame for then feeding a sealing strip of a substantially U-shaped cross section and a length at least equal to the circumference of said edges to said sealing rollers so that the two webs of said strip enter between said sealing rollers and said edges, whereby said sealing rollers while turning said container and cover together with said strip for at least one complete revolution will press said webs toward each other and thereby deform them around said edges so as to seal said container tightly, said elevating means then being adapted first to release said sixth means so that said resilient fourth means will move said lower sealing roller back to its retracted position and then to lower said centering plate with said sealed container to said normal level, and means for then ejecting said sealed container from said table surface.
 2. A sealing machine as defined in claim 1, further comprising a substantially vertical post having a housing on its upper end, said shafts extending through said housing and carrying said sealing rollers outside of said housing, said first, second, fourth, and sixth means being connected to and at least partly disposed within said housing, and manually operated means for moving at least said housing in a substantially horizontal longitudinal direction and for raising and lowering it in a substantially vertical direction, relative to said frame in order to permit the position of said sealing rollers to be adjusted in accordance with different series of containers of different heights and/or different diameters prior to the operation of said machine of sealing each of said different series.
 3. A sealing machine as defined in claim 2, in which said second and sixth means comprise a bearing sleeve, said lower shaft extending through and rotatably guided by said bearing sleeve but nonslidable in its axial direction relative to said sleeve, said bearing sleeve having opposite plane outer surfaces parallel to each to other, at least two pairs of guide rollers rotatably mounted on said outer surfaces of said sleeve and spaced from each other, the guide rollers of each pair having a common axis extending transverse to the common longitudinal axis of said sleeve and said lower shaft, at least two pairs of bearing members rigidly secured to said housing, said bearing members of each pair having plane parallel surfaces facing and spaced from each other and extending in vertical directions, said plane outer surfaces of said bearing sleeve being disposed between and slidably guided in vertical directions by said plane surfaces of said bearing members, said bearing members haVing cam-shaped front surfaces, each of said cam surfaces having an upper part projecting more forwardly than the lower part, said resilient fourth means comprising tension springs connected to said bearing sleeve and to a rear part of said housing for maintaining said guide rollers on said bearing sleeve in constant engagement with said cam-shaped front surfaces and tending to draw said bearing sleeve downwardly and toward the rear, a shaft rotatably mounted in a fixed position in said housing underneath said bearing sleeve and extending parallel thereto, at least one lever secured at one end to said last shaft, and cam members secured to said last shaft and by the action of said tension springs being at all times in engagement with the lower side of said bearing sleeve, and at least one Bowden cable having one end connected to said fifth means and another end connected to the other end of said lever so that, when said centering plate has been raised sufficiently to lift said rolled edges past said lower roller, said other end of said lever will be pulled downwardly and said cam members on said last shaft will thereby be pivoted upwardly, whereby due to the engagement of said guide rollers with said cam-shaped front surfaces of said bearing members, said bearing sleeve together with said lower shaft and sealing roller will be moved in the axial direction toward said container and then upwardly so as to press said lower sealing roller against said rolled container edge.
 4. A sealing machine as defined in claim 1, in which said fifth means comprise hydraulic means, and further comprising hydraulic means responsive to the lowering of said centering plate for actuating said ejecting means.
 5. A sealing machine as defined in claim 1, in which said strip-feeding mechanism comprises a reel rotatably and removably mounted on said frame and carrying a supply of a flat strip material, and means for withdrawing said strip material from said reel, for bending said material to a substantially U-shaped cross section to form a sealing strip, for cutting off a section of said material of a predetermined but adjustable length as required for the following sealing operation and for feeding said sealing strip to said sealing rollers, and means responsive to the movement of a container to said sealing station for starting said feeding mechanism. 6 A sealing machine as defined in claim 1, in which said conveying means comprise a conveyor of, and driven by, a preceding machine and connected to said sealing machine so as to feed a new container to be sealed to said sealing station immediately prior to the beginning of the operation of said sealing machine or when the previously sealed container has been moved off said station, and means for detecting the arrival of a container at said sealing station and for then starting the operation of said fifth means.
 7. A sealing machine as defined in claim 1, in which said conveying means are driven by the driving means of said sealing machine.
 8. A sealing machine as defined in claim 1, in which said conveying means comprise a turntable rotatable about a central vertical axis, means for feeding containers to a receiving station of said turntable, continuously rotatable driving means for said conveying means, and means interposed between and connected to said driving means and said turntable for converting the continuous rotation of said driving means into an intermittent rotation of said turntable, each stop of said turntable having a length at least equal to one complete sealing operation including the lifting and lowering of a container by said centering plate at said sealing station, said turntable comprising a larger lower plate and a smaller upper plate concentrically secured to each other, said lower plate having a plurality of circular apertures equally spaced from said vertical axis and equally spaced peripherally from each other and each adapted to receive one of said centering plates having an upper surface normally disposed at the level of the upper surface of said lower plate forming said table surface, said upper plate having substantially semicircular outwardly open pockets in its outer peripheral wall, each of said pockets being coaxial with one of said apertures and, when stopped at said receiving station, being adapted to receive a container from said container-feeding means and to center it on said centering plate at said receiving station and to hold it thereon until said container reaches said sealing station and is then lifted by said centering plate, sealed, and lowered to said normal level, and said sealed container is then ejected from said turntable by said reflecting means.
 9. A sealing machine as defined in claim 8, further comprising a segmentally-shaped guide rail mounted in a fixed horizontal position underneath said turntable and extending from a point near and forwardly of said receiving station to a point forwardly of said sealing station, as seen in the direction of rotation of said turntable, each of said centering plates being secured to the upper end of a spindle, a vertical guide tube for each spindle secured to said lower plate, and a small roller rotatably mounted on the lower end of each spindle projecting from said guide tube, said roller being adapted to roll upon and along said guide rail when a container is moved by said turntable away from said receiving station, whereby said centering plate carrying said container is lifted for a short distance above said normal level and engages into the hollow bottom of said container so as further to center and hold said container within its pocket of said upper plate during the further rotation of said turntable until said pocket has passed sealing station.
 10. A sealing machine as defined in claim 8, in which said container-feeding means comprise a conveyor continuously driven by said driving means, said lower plate having a radial first slot extending from each of said apertures to the periphery of said lower plate, the last section of the conveying surface of said conveyor adjacent to said turntable having a second slot adapted to be in straight alignment with the first slot in said lower plate at said receiving station, a feed rod underneath said second slot in said conveying surface, a small angular feed lever pivotably mounted on said feed rod and pivotable through said second slot, a spring tending to pivot said feed lever so that the free end thereof projects slightly above said conveying surface, a crank drive also driven by said driving means for said conveying means for reciprocating said feed rod to and from said turntable and for thus moving said feed lever along said second slot and said first slot at said receiving station, and means for arresting the forward movement of a second container on said conveyor during at least the last part of the rearward stroke of said feed rod, so that said feed lever can then slide underneath the first, forwardly moving container on said conveyor and then pivot upwardly and hook behind the bottom of said first container and, by the following forward stroke of said feed rod, move said first container into said pocket at said receiving station.
 11. A sealing machine as defined in claim 8, in which said ejecting means comprise a deflecting member adjustable so as to extend at a certain fixed angle to the direction of rotation of said turntable to permit the sealed container to abut against and slide along said deflecting member during the further rotation of said turntable. 